docs: def write_merged_bioassembly(inpath, outdir, outname, force_rerun=False):
      """Utility to take as input a bioassembly file and merge all its models into multiple chains in a single model.
  
      Args:
          infile (str): Path to input PDB file with multiple models that represent an oligomeric form of a structure.
          outdir (str): Path to output directory
          outname (str): New filename of structure file
          force_rerun (bool): If a new PDB should be written if the file exists
  
      Returns:
          str: Path to newly written PDB file.
  
      """
      outpath = outfile=op.join(outdir, outname + '.pdb')
  
      if ssbio.utils.force_rerun(flag=force_rerun, outfile=op.join(outdir, outname + '.pdb')):
          s = StructProp('Model merging', structure_path=inpath, file_type='pdb')
          ss = s.parse_structure()
          merge_all_models_into_first_model(ss.structure)
          outpath = ss.write_pdb(custom_name=outname, out_dir=outdir, force_rerun=force_rerun)
      else:
          return outpath